Two years ago, Emily St John Mandel was promoting The Glass Hotel, her fifth novel, when the pandemic broke out and the world shut down. It was a weird time for everyone, but for the 42-year-old novelist, whose previous book, Station Eleven, had imagined a post-apocalyptic world 20 years after a deadly pandemic killed 99% of the population, it was particularly strange. Nobody wanted to talk about The Glass Hotel. Instead, Mandel was feted as clairvoyant, asked to predict what might happen next, and invited, she says now, to “treat the pandemic as a way to sell copies of Station Eleven”. The novel itself, meanwhile, went from being simply a hit to the kind of book from which fans lift lines to have tattooed on their arms.

All of this, while alarming the author, also struck her as interesting at the narrative level. Mandel’s new novel, Sea of Tranquility, revisits aspects of her pandemic experience, although as one might imagine from a writer interested in building alternative worlds, not in a conventional style. So while the protagonist, Olive Llewellyn, is an author whose book tour is disrupted when a global pandemic, “Sars Twelve”, breaks out, the year is 2203 and all major cities in what was once the United States exist under climate-controlled domes. There are multiple colonies on the moon. Mandel also ranges back to 1912 and jumps ahead to 2401, and while portals for time travel and commuting by spaceship both feature, the most trenchant and mordantly funny parts of the novel involve all the ways in which, hundreds of years into the future, not much has changed. Whatever the date and the state of humanity, there will always be red velvet cupcakes, and misogyny.

Olive, in 23rd-century New York, is asked a question by an interviewer that Mandel herself was once asked on a book tour – “by a woman in Odessa, Texas”, she says, looking scandalised afresh. We are in the kitchen of the apartment in Greenwood, Brooklyn, where Mandel lives with Kevin, her husband, and their five-year-old daughter. The woman in question, she recalls, said: “You must have a very kind husband to look after your daughter while you do this!” Mandel trained as a dancer and holds herself straight-backed, with a poise suggestive of coiled energy before movement. “And there was so much to unpack that my brain just seized and I had nothing to say.” She adds, drily: “The list of things that men on business trips absolutely do not hear.”

The novel’s title refers to a section of the moon not far from where the Apollo 11 astronauts landed, and where, when she is not on a book tour on Earth, Olive lives with her husband and daughter. One question the novel explores is what it is like to move so far from your roots that you effectively live in an entirely new world. For the occupants of the Night City, the moon’s second colony, the lost world is Earth. For a character called Edwin St Andrew St John – a long-winded surname the author borrowed from her own great-grandfather, Newell St Andrew St John – the point of origin is British India, “a weird lost world”, says Mandel, “and of course it has a colonial heart of evil at the base of it. At the same time, I was thinking how the world changes and leaves us a little bit stranded, sometimes, at these points in history. It’s fascinating and strange.”

These themes are personal to the author, who grew up in Denman Island, an area of 20sq miles off the coast of British Columbia with a population of about 1,000. The distance travelled from her childhood home to Brooklyn is tremendous in more ways than one. “It’s a weird thing,” she says, “where on the one hand, my present life feels somewhat improbable in the context of my childhood; on the other hand, my childhood did not feel exotic. The important distinction about somewhere like Denman Island is that it’s rural but it’s not remote. It’s not like I would know what to do if I encountered a bear, for example. That wasn’t part of the training. I mean the bears would have to swim to get there, so.” She thinks for a moment. “I’m perhaps better than the average New Yorker at walking through forest. That’s as far as it goes.”

Mandel’s childhood was untypical in other ways, too. The second of five siblings, she was homeschooled until the age of 15. Her parents – her dad, a gas fitter and plumber, and her mother, who worked for domestic violence and homelessness charities – created an unconventional home in a place with no building codes. “There was a pillar that supported part of the living room ceiling that was a massive tree, with the bark carved away. It was beautiful and interesting.” But she points out: “There’s no municipal water system in a place like that. So we would draw water from the deep well, which would go dry in the summer and we’d switch to the cistern, which pumped water something like six acres uphill from a creek that we had water rights to. And it was quite elaborate and challenging.” When I ask if a certain inner ruggedness derives from these things, she laughs loudly and suggests that the skill it taught was weathering inconvenience, rather than survivalism.

A benefit of home schooling was that she had to write, creatively, every day, and did so from the age of eight or nine. Mandel wanted to be a dancer and, at 18, left the island to take up a scholarship at the School of Toronto Dance Theatre, where she studied for four years. For the next decade, she would write in the off hours around modestly paid day jobs. Her first novel, Last Night in Montreal, was published in 2009 and revolves around the mystery of a kidnapped child. It was respectfully reviewed without making much of a ripple. Two more followed, The Singer’s Gun and The Lola Quartet. Her fourth novel, Station Eleven, was her last attempt to break through before giving up. She was in the world of “$32 royalty cheques and bookstore events to which four people turn up. It felt impossible.” The hype around Station Eleven was immediate and huge, but for a long time Mandel didn’t give up her job as an administrator at the Rockefeller University in Manhattan.

“I’m from a working-class background and I think that, psychologically, that makes it quite difficult to quit your day job and have no safety net.” She held on to the post until “it really made no sense. I was working remotely, and it was a strange period – I remember a day when I had to leave work early because I had a photoshoot at the Time-Life building. One of my jobs was booking plane tickets for my boss. Meanwhile, I didn’t book my own plane tickets; a publicist did that. It was so odd.” What persuaded her in the end was finding out that she was pregnant. “It was one too many things. Something had to go and it had to be the day job.”

Station Eleven was unusual apocalypse literature in that, in some ways, it was really quite cheering. While there were horrifying elements, unlike in a Cormac McCarthy novel, post-civilisation wasn’t one long cannibalistic nightmare. People worked together and formed communities. They remembered Shakespeare. That is why, perhaps, the book became so popular again during the pandemic. It soothed us by simultaneously showing a much worse scenario than the one we were in, while reassuring us that nice things about humanity survived. “There is such a clear message of continuing after the pandemic, and I think that’s what people responded to. It was a big part of the appeal.”

The novel’s success was also down to Mandel’s subtlety as a writer. The scene that still lingers in my mind is the image of the plane on the runway, full of passengers with the virus, who, in an act of self-sacrifice, never disembark and come into the airport. “You don’t want to think about it,” she says. “My general approach to horror is you can just suggest it; you don’t have to go into the gruesome last hours. You can just say: nobody ever came out.”

The TV adaptation of Station Eleven recently aired on HBO Max and on StarzPlay in the UK, a 10-part series by Patrick Somerville that thoughtfully and successfully interprets Mandel’s story. The book, meanwhile, was shortlisted for the National Book and PEN/Faulkner awards, and won the Arthur C Clarke award. Nonetheless, the author was startled when, at a book signing, someone lifted his sleeve to reveal a line from the novel – “survival is not enough” – inked on his arm. Since then, she has seen “probably a dozen tattoos, and that blows my mind. It’s destabilising. The idea that you write something fictional and all of a sudden it appears before you in the world. It’s hard to wrap my head around.”

Characters move across Mandel’s books. Bit characters in one become heroes in another. Figures in The Glass Hotel duly appear in Sea of Tranquility. “Character development is hard. If you already have someone in the wings that you can just pull out on stage, that is part of the temptation. Also, I have some desire to – this is going to sound pretentious, but – build a multiverse.” She laughs. “There’s something about building a unified world where the books connect, even though they all stand alone, that appeals to a certain longing for order that I have. People come back and it all ties together.” Yes, I agree; why shouldn’t literary novelists create worlds on a par with Marvel and DC. You could have merch. “Station Eleven T-shirts!”

The Glass Hotel was brutal to write, explains Mandel. “Horrible,” she says. “My first round of editorial notes were really hard. They could be summarised as: could you please change everything, the structure, the characters, the plot. Nothing was working. I probably spent a couple of days crying on the floor of my office and then I got up and started revising.”

What was the problem? “There was just a weight of expectation following Station Eleven that I’d never had before and which, to be clear, is not a problem. I don’t want to complain; I won the lottery here.” And she was grateful for the edits. “You never want to become one of those authors who becomes more and more successful and the books become longer and longer and longer, and worse and worse.” Still, it was painful, and took a long time to write.

The novel is loosely based on the story of Bernie Madoff, and the act of dreaming her way into the head of someone in finance was, she laughs, in some ways harder than imagining time travel. “I bought a couple of books on economics, but I don’t speak the language so I couldn’t get very far. I did enough research to drop in a couple of somewhat plausible lines that might indicate a finance background. But then researching Madoff’s Ponzi scheme was really interesting. It is such a human story. You get past the finance details pretty quickly, and then it’s a story about a conman.”

By contrast, writing Sea of Tranquility was relatively easy, in spite of, or even in some ways because of the pandemic. Mandel’s daughter was at nursery school in March 2020, and after they pulled her out she didn’t return for a year. (“Eventually we got into a nanny share, three families, and that saved our sanity and made it possible to work.”) Psychologically, the condition of the world outside quietened some inner anxiety. “There was something kind of creatively liberating about writing the novel during the worst of the pandemic. In your normal life, writing a novel is hard. But when everything was so horrible, writing the novel felt like no big deal.”

Life is more or less back to normal now. Mandel’s husband, an executive recruiter, goes into his office in midtown a few days a week. She is thinking of returning to the gym. Her child is in school. Her next book deadline isn’t for another four years, and in the meantime, she might try to write for TV. Looking back on lockdown, however, she wonders if, for a short while, it really did usher in the kind of healthy detachment usually wholly unattainable to the writer. “The world is a mess” – she smiles at the novelty of the thought – “who cares if this book is good?”

• Sea of Tranquility by Emily St John Mandel is published by Picador.

• This article was amended on 11 April 2022 to correctly refer to Emily St John Mandel as “Mandel” rather than “St John Mandel”. St John is the author’s middle name.